filipecbv
Newbie level 6
charge pump ac analysis
Hi,
I'm designing a charge pump (phang topology) for memories, using a clock of 100kHz. The charge pump is working, but I'm having a difficult to analyze it in terms of stability.
I want to control the output voltage changing the amplitude of the clock signal, so I modeled my charge pump.
Then, one pole is created in the charge pump being an association of the output resistance of the charge pump (30Mohm) with the output capacitor (10pF), and resulting in a pole of 1kHz. So, the requirements of the opamp to control the system is as small as 1kHz.
The output resistance of the charge pump is given by n/c.f, where n=6, c=3p and f=100kHz.
Could be this analysis wrong?
What are good references to read about the stability of charge pumps?
I didn't found papers about this fact, mainly related to this pole that I found, and what to do with it.
Thanks
Filipe
Hi,
I'm designing a charge pump (phang topology) for memories, using a clock of 100kHz. The charge pump is working, but I'm having a difficult to analyze it in terms of stability.
I want to control the output voltage changing the amplitude of the clock signal, so I modeled my charge pump.
Then, one pole is created in the charge pump being an association of the output resistance of the charge pump (30Mohm) with the output capacitor (10pF), and resulting in a pole of 1kHz. So, the requirements of the opamp to control the system is as small as 1kHz.
The output resistance of the charge pump is given by n/c.f, where n=6, c=3p and f=100kHz.
Could be this analysis wrong?
What are good references to read about the stability of charge pumps?
I didn't found papers about this fact, mainly related to this pole that I found, and what to do with it.
Thanks
Filipe